Observational astronomers use telescopes that look at the furthest distances in the Universe to look back in time and trace the growth of structure in the cosmos. Recent multi-wavelength measurements have helped us to constrain the components that make up the Universe and how those components evolve. We now know that most of the Universe is made up of dark matter and dark energy, but the nature of these components remains largely unknown. In this talk I will give an overview of the techniques used to map the universe on the largest scales, which have enabled us to measure dark energy and dark matter.